A typical automobile air conditioner includes a compressor, a condenser, an expansion valve, and an evaporator. The compressor compresses a cool vapor-phase refrigerant (e.g., freon, R134a) to heat the same, resulting in a hot, high-pressure vapor-phase refrigerant. This hot vapor-phase refrigerant runs through a condenser, typically a coil that dissipates heat. The condenser condenses the hot vapor-phase refrigerant into liquid refrigerant. The liquid refrigerant is throttled through an expansion valve, which evaporates the refrigerant to a cold, low-pressure saturated liquid-vapor-phase refrigerant. This cold saturated liquid-vapor-phase refrigerant runs through the evaporator, typically a coil that absorbs heat from the air fed to the passenger compartment.
An automobile air conditioner consumes much engine power, which negatively impacts the acceleration performance and fuel economy. Attempts have been made to improve the air conditioner""s efficiency by capturing some of the energy released by the hot, high-pressure refrigerant during the expansion stage, and applying the recovered energy toward compressing the cool vapor-phase refrigerant.
When a high-pressure, liquid refrigerant is throttled through an expansion valve or an orifice, it is transformed into a cold low-pressure saturated liquid-vapor-phase refrigerant, which is known as the xe2x80x9crefrigeration effect.xe2x80x9d The throttling process itself does not fundamentally change the enthalpy (energy) content of the liquid-phase refrigerant. The liquid-phase to saturated liquid-vapor phase transformation, however, creates a boiling effect that liberates much kinetic energy, lowering the temperature of the refrigerant. The refrigerant""s pressure drop from the high side to the low side and its subsequent expansion during cavitation (liquid-phase to saturated liquid-vapor-phase) provides an excellent opportunity to extract mechanical work. Further, extracting work from the refrigerant will enhance the refrigeration cycle performance, since the energy content of the refrigerant is reduced. It is desirable to capture this kinetic energy as much as possible.
In this regard, Japanese Patent publication Nos. 11-063707, 4-340062, and 61-96370, for example, disclose substituting the expansion valve with an expansion machine to capture part of the kinetic energy liberated during the throttling process. The expansion machine is essentially a motor driven by the hot, high-pressure liquid-phase refrigerant as it evaporates to a cold, low-pressure saturated vapor-phase refrigerant. A motor can include any device which produces energy resulting from the expansion of the refrigerant. The motor in turn is connected to a supercharger or compressor that can partially compress all or some of the cool vapor-phase refrigerant exiting from the evaporator, upstream of the compressor. The compressed refrigerant is fed through the compressor or fed to the condenser. Ideally, this should reduce the energy required to compress the refrigerant, thus making the air conditioner more efficient.
The present inventor had discovered that work can be best captured when the refrigerant is undergoing transformation from a liquid phase (or saturated liquid-vapor phase) to a saturated liquid-vapor phase having a higher vapor content, which occurs in a xe2x80x9chigh cavitationxe2x80x9d region. Keeping the refrigerant in a high cavitation region within the motor, however, is difficult. The present inventor had discovered a way of maintaining the location of the high-cavitation region as the refrigerant is passed through an energy recovery device. The teachings of the present inventor""s discovery can be found in U.S. Pat. No. 6,272,871, which is incorporated herein by reference in its entirety.
It is known that when fluid flow is suddenly started and/or suddenly stopped and/or suddenly restricted and/or suddenly increased, audible sounds and other vibrations are sometimes generated. These sounds may include but are not limited to a bang, a knock, a clunk, a clang, etc., and may also include multiple variations, combinations, and repetitions thereof. Generally, it is believed that the sounds and vibrations are a result of a pressure wave traveling down, say, a pipe or any other form of fluid conduit. This phenomenon is commonly referred to as water hammer. It is also believed that other sounds not commonly referred to as water hammer are generated when a fluid flow is suddenly started and/or suddenly stopped. It is also believed that suddenly restricted and/or suddenly increased flows generate sounds not commonly referred to as water hammer.
The present inventor has discovered that practicing the teachings of U.S. Pat. No. 6,272,871 can lead to the creation of sounds including but not limited to the sounds described above. It is believed that the sounds are related to maintaining the location of the high-cavitation region as the refrigerant is passed through the energy recovery device. Specifically, it is believed that the sounds result from the refrigerant flow stopping abruptly and/or slowing abruptly when the flow of refrigerant through the motor is regulated by the energy recovery device, and it is also believed that it is possible that the sounds result from the refrigerant flow slowing abruptly and/or increasing speed abruptly when the flow of refrigerant through the motor is regulated by the energy recovery device.
The present invention relates to an air conditioner comprising at least one evaporator that evaporates a cold refrigerant, at least one heat removal device adapted to receive compressed refrigerant and remove heat from at least a portion of the compressed refrigerant, at least one energy recovery device, wherein the energy recovery device comprises at least one motor, the at least one motor being in fluid communication with the at least one heat removal device and positioned downstream of the heat removal device and upstream of the evaporator, and a sound suppression device in fluid communication with the heat removal device and the motor and positioned upstream of the energy recovery device.
According to another aspect of the invention, the sound suppression device comprises a reservoir adapted to hold varying mass amounts of refrigerant.
According to another aspect of the invention, the reservoir is adapted to be filled and depleted with refrigerant.
According to another aspect of the invention, the reservoir is adapted to be filled and depleted with liquid refrigerant.
According to another aspect of the invention, the reservoir is a high-pressure reservoir.
According to another aspect of the invention, the sound suppression device comprises an orifice adapted to suppress sound resulting from operation of the energy recovery device.
According to another aspect of the invention, the sound suppression device comprises an orifice adapted to dampen a pressure pulse or a pressure wave propagating from a location at or upstream from the energy recovery device and downstream from the sound suppression device.
According to another aspect of the invention, the sound suppression device further comprises an orifice in fluid communication with the heat removal device and the reservoir.
According to another aspect of the invention, the orifice is positioned upstream of the reservoir.
According to another aspect of the invention, the orifice is integral with the reservoir.
According to another aspect of the invention, the energy recovery device is adapted to pulsatingly control the flow of refrigerant through the motor.
According to another aspect of the invention, refrigerant flow into the sound suppression device is continuous during steady-state operation of the air conditioner.
According to another aspect of the invention, refrigerant flow from the heat removal device is continuous.
According to another aspect of the invention, refrigerant flows into the sound suppression device after the refrigerant flow is substantially restricted from flowing to the motor.
According to another aspect of the invention, refrigerant flows into the sound suppression device after the refrigerant flow is substantially restricted from flowing from the motor.
According to another aspect of the invention, the sound suppression device is adapted to prevent a sudden increase in refrigerant pressure upstream from the energy recovery device when the energy recovery device pulsatingly controls the flow of refrigerant through the motor.
According to another aspect of the invention, energy of a pressure pulse created by the energy recovery device resulting from the energy recovery device pulsatingly controlling the flow of refrigerant through the motor is substantially reduced.
According to another aspect of the invention, the time for the pressure to rise at a location upstream from the energy recovery device and downstream from the heat removal device when the energy recovery device pulsatingly controls the flow of refrigerant through the motor is substantially extended.
According to another aspect of the invention, the sound suppression device reduces water hammer.
According to another aspect of the invention, the sound suppression device substantially reduces water hammer noise.
According to another aspect of the invention, the sound suppression device substantially absorbs a pressure pulse created when the energy recovery device pulsatingly controls the flow of refrigerant through the motor.
According to another aspect of the invention, the sound suppression device comprises a reservoir, wherein the reservoir is filled with refrigerant, the refrigerant being in at least one of a liquid and a liquid-vapor state.
According to another aspect of the invention, the sound suppression device comprises a pressure regulator.
According to another aspect of the invention, the sound suppression device decreases the rate of pressure increase of the refrigerant at a location upstream from the energy recovery device and downstream from the heat removal device as compared to the rate of pressure increase in an air conditioner without the sound suppression device.
According to another aspect of the invention, there is an air conditioner comprising an evaporator that evaporates a cold refrigerant to a vapor phase, a main compressor connected to the evaporator so that the compressor receives the vapor-phase refrigerant from the evaporator and compresses the vapor-phase refrigerant, a heat removal device connected to the compressor so that the heat removal device receives the compressed refrigerant from the compressor and removes heat from the refrigerant, an energy recovery device connected to the heat removal device and the evaporator so that the compressed and cooled refrigerant is passed through the energy recovery device, and a sound suppression device in fluid communication with the heat removal device and the energy recovery device and positioned upstream of the energy recovery device, wherein the energy recovery device includes, a motor located downstream of the heat removal device and upstream of the evaporator, and a regulator that passes the compressed and cooled refrigerant into the motor and maintains the refrigerant in the motor in a high cavitation region, while maintaining refrigerant within a predetermined refrigerant pressure range in the motor, wherein the regulator releases the refrigerant to the evaporator in a first saturated liquid-vapor phase having a higher vapor content than the refrigerant exiting the heat removal device.
According to another aspect of the invention, the regulator comprises a valve located adjacent the motor, the valve opening and closing flow of refrigerant through the motor, and a controller for opening and closing the valve based on the pressure of the refrigerant downstream of the motor and upstream of the evaporator to regulate the refrigerant flowing into the motor and maintain the refrigerant in a high cavitation region within the motor, while maintaining refrigerant within the predetermined refrigerant pressure range in the motor.
According to another aspect of the invention, there is a method of suppressing sound resulting from recovering energy from an air conditioner having an evaporator that evaporates a cold expanded refrigerant, a heat removal device adapted to receive compressed refrigerant from a compressor and remove heat from at least a portion of the compressed refrigerant, and an energy recovery device having a motor, the method comprising, providing a sound suppression device in fluid communication with the heat removal device and the energy recovery device and positioned upstream of the energy recovery device, passing the cooled refrigerant through the motor, regulating the flow of the refrigerant through the motor and maintaining the refrigerant in a high cavitation region within the motor, and suppressing sounds resulting from the regulation of the flow of the refrigerant.
According to another aspect of the invention, the sounds are suppressed by dampening pressure pulses or pressure waves resulting from the regulation of the flow of the refrigerant.
According to another aspect of the invention, the sounds are suppressed by enabling flow into the sound suppression device to be continuous.
According to another aspect of the invention, the sounds are suppressed by enabling flow into the sound suppression device to continue after the flow through the motor is restricted.
According to another aspect of the invention, the rate of pressure increase of the refrigerant at a location upstream from the energy recovery device and downstream from the heat removal device is decreased as compared to the rate of pressure increase in an air conditioner without the sound suppression device.
According to another aspect of the invention, the sounds are suppressed by enabling flow from the heat removal device to be substantially continuous.
According to another aspect of the invention, the sounds are suppressed by preventing a sudden increase in refrigerant pressure upstream from the energy recovery device when the flow of refrigerant is regulated.
According to another aspect of the invention, there is an air conditioner comprising, at least one evaporator that evaporates a cold refrigerant, at least one heat removal device adapted to receive compressed refrigerant and remove heat from at least a portion of the compressed refrigerant, at least one flow restriction device adapted to abruptly decrease the flow of refrigerant from the heat removal device towards the evaporator at at least one location between the heat removal device and the evaporator, and a sound suppression device in fluid communication with the heat removal device and the evaporator and positioned upstream of the flow restriction device and downstream of the heat removal device.
According to another aspect of the invention, refrigerant flows into the sound suppression device after refrigerant flow is substantially restricted from flowing towards the evaporator.
According to another aspect of the invention, the sound suppression device is adapted to prevent a sudden increase in refrigerant pressure upstream from the flow restriction device when the flow restriction device restricts the flow of refrigerant towards the evaporator.
According to another aspect of the invention, energy of a pressure pulse created by the flow restriction device resulting from the flow restriction device restricting the flow of refrigerant towards the evaporator is substantially reduced.
According to another aspect of the invention, the time for the pressure to rise at a location upstream from the flow restriction device and downstream from the heat removal device when the flow restriction device restricts the flow of refrigerant towards the evaporator is substantially extended.